/*
 * Copyright 2013 Robert Peszek.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package fpig.lists.functions

import fpig.concepts.MonadDescription;
import fpig.lists.structures.FunList;
import fpig.util.CallUtil;
import groovy.lang.Closure;

import static fpig.lists.functions.Base.*

/**
 * Describes FunList as Monad.
 *
 * TODO document
 * @author robert peszek
 *
 */
class FunListMonad<A> extends MonadDescription<A, FunList<A>>{
   static FunListMonad instance = new FunListMonad() //@Singleton annotation does not want to work!
   
   Closure getPure(){
	  {A a -> e(a) << empty() }
   }
	
   Closure getBind(){
	   CallUtil.toFunction {Closure c, FunList<A> m-> 
		   def res = concat << map(c) << m
		   res
	   }
   }
   
   static Closure p = FunListMonad.instance.pure
   
}
